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# AudioUnitParameter

An adjustable audio unit attribute such as volume, pitch, or filter cutoff frequency.

```
struct AudioUnitParameter
```

## Overview

This data structure is used by functions declared in the `AudioToolbox/AudioUnitUtilities.h` header file in macOS.

An audio unit parameter is uniquely identified by the combination of its scope, element, and ID.

## Topics

### Initializers

[`init(mAudioUnit: AudioUnit, mParameterID: AudioUnitParameterID, mScope: AudioUnitScope, mElement: AudioUnitElement)`](/documentation/AudioToolbox/AudioUnitParameter/init(mAudioUnit:mParameterID:mScope:mElement:)-2hcn6)

[`init(mAudioUnit: AudioUnit, mParameterID: AudioUnitParameterID, mScope: AudioUnitScope, mElement: AudioUnitElement)`](/documentation/AudioToolbox/AudioUnitParameter/init(mAudioUnit:mParameterID:mScope:mElement:)-55k5j)

### Instance Properties

[`var mAudioUnit: AudioUnit`](/documentation/AudioToolbox/AudioUnitParameter/mAudioUnit)

The audio unit instance that the parameter applies to.

[`var mElement: AudioUnitElement`](/documentation/AudioToolbox/AudioUnitParameter/mElement)

The audio unit element for the parameter.

[`var mParameterID: AudioUnitParameterID`](/documentation/AudioToolbox/AudioUnitParameter/mParameterID)

The audio unit parameter identifier.

[`var mScope: AudioUnitScope`](/documentation/AudioToolbox/AudioUnitParameter/mScope)

The audio unit scope for the parameter.

## Relationships

### Conforms To

[`BitwiseCopyable`](/documentation/Swift/BitwiseCopyable)

---

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